Optimization of regional storm-water management systems

In order to mitigate the adverse impacts of urban drainage, storm-water detention ponds are commonly used in watersheds undergoing urban development. These ponds may occupy valuable land and involve initial construction, operation, and maintenance costs. The objective of land developers and/or municipalities is to minimize these costs while satisfying regional environmental regulations for runoff quantity and quality control. An optimization methodology is presented for determining the design parameters (storage volume, release rate, and pond depth) of a single storm-water management pond. The methodology is extended, using a dynamic programming procedure, to a multiple parallel catchment system (each with a single detention pond). The least-cost values of pond design variables are subjected to system performance constraints, in the form of specified levels of runoff and pollution control at the outfall to a receiving water. The model inputs are statistics of meteorologic records, catchment hydrological parameters, land and construction costs, and permissible pond depth ranges. The model output provides optimal (least-cost) values of design variables for desired levels of runoff and pollution control.